Fluidic fluid metering system

ABSTRACT

In a fluidic metering system having a return line, a means is provided of reducing or completely eliminating the back pressure effects of the fluid in the return line on the fluidic portion of the system. The means comprise a jet pump operative to draw excess or unmetered fluid away from the fluidic portion of the system and to provide the fluidic portion of the system with a stable back pressure.

United States Patent Sulich [451' Oct. 17, 1972 [541 FLUIDIC FLUIDMETERING SYSTEM 3,469,593 9/1969 OKeefe ..'.l37/81.5 72 I t I f D 3,477,699 11/1969 Drayer ..l37/8l.5.X 1 Janus s 3,556,488 1/1971 Arikawa et a1 ..137/81-.5 x [73] Assignee: The Bendix Corporation 3,564,844 2/1971 Rimmer ..137/81.5 X [22] Filed Sept 15 1969 3,565,091 2/1971 Auger ..l37/81.5

[21] Appl. No.: 858,021 Primary Examiner-Samuel Scott Attorney-Robert A. Benziger and Plante, Arens, U S 137/81 5 Hartz, Hi): and Smith [5 Int. [58] Field of Search ..l37/8l.5; 417/54 1 In a fluidic metering system having a return line, a [56] References Cited means is provided of reducing or completely eliminating the back pressure effects of the fluid in the return UNlTED STATES PATENTS line on the fluidic portion of the system. The means comprise a jet pump operative to draw excess or un- Z 9 i. metered fluid away from the fluidic portion of the I op m l system and to provide the fluidic portion of the system Cawley 1 1 a Stable back pressure. 3,429,324 2/1969 Brown et a1. ..137/81.5 3,438,384 4/1969 Hurvitz ..137/8l.5 6 Claims, 2 Drawing Figures I IV I BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the art of fluid handling and metering systems and particularly those systems which control the flow of fuel for mixture with air prior to combustion in an engine. More specifically, thepresent invention relates to fuel systems which incorporate one or more fluid amplifier elements to control the fuel delivery.

2. Description of the Prior Art A wide variety of fluid flow controlling systems are known in the art. Such systems as utilize one or more fluidic elements are also known and are of recent advent in the art of fuel control and metering for combustion engines. Examples of these systems may be found in U.S. Letters Pat. No. 3,386,710 issued to J. B. York, Jr., U.S. Pat. No. 3, 389,894 issued to A. M. Binderand U.S. Pat. No. 3,406,951 issued to C. Marks, to name a few. While the systems disclosed in the referenced patents utilize fluidic elements, they should not be thought of as complete fuel systems since these systems utilize an essentially constant fuel/air ratio whereas, in an engine operating cycle, the fuel/air ratio must be varied to provide various enriched ratios such as cold start, full load, acceleration, and wide-open throttle enrichment. All of these variously ratioed enriched mixtures may be provided by controllably altering the control signals to the primary control element through additional fluidic control circuitry. However,

and interaction region of the fluidic amplifier means resulting in an undesirably high quantity of fuel being directed to the outlet port associated with the air intake of the internal combustion engine causing the fuel/air ratio to be higher than required for best engine and emissions control performance.

On the other hand, vehicle accelerations could causefuel in the return-line to flow away from the fluid logic o computing means at a higher flow rate than normal thereby causing a low pressure zone to form adjacent the power stream which would be operative to divert a larger portion of the power stream intothe return-line systems that provide accurate fuel/air ratios in tests simulating all engine operating requirements suddenly become highly inaccurate mis-approximations when these identical systems are installed in vehicles wherein the system is subjected to varying return fuel pressure due to attitudes or dynamic motions of the vehicle.

It is a characteristic of the known fluidic fuel systems that the main, or primary fluidic stage comprises a nozzle for discharging pressurized fluid into a fluid interaction region where control signals, disposed laterally of the fluid stream, deflect the stream towards one of a pair of outlets. In systems where the fluid is fuel, one outlet port is in communication with a-fuel discharge nozzle while the other outlet permits fuel entering thereinto to return to the fuel tank. In such systems, when installed in vehicles, it has been found that vehicle attitude, accelerations and decelerations to which the vehicle is subjected and combinations thereof, produce forces which are not instantly transmitted to the fuel in the vehicles fuel system thereby causing undesired variations in the fuel pressure within the fuel system. This effect is not particularly noticeable on the fluid which is upstream from the fluidic amplifier means power nozzle. However, the effect is quite noticeable on the fuel in the return line which, in most instancesmust run the length of the automobile in the direction of greatest variations in acceleration. For instance, the vehicles decending a grade or a deceleration of the vehicle caused by braking will cause the fuel in the return line to tend to travel toward the front of the vehicle. In most cases, this would mean that returnline fuel is traveling toward the return-line inlet. Since this would also be at the fluid interaction region of the fluidic computation means, the result would be a relatively sudden increase in the pressure at the outlet ports port. The fuel/air ratio would then become leaner than desired. As a result, it has become'evident that fluid logic fuel systems, at least as applied in vehicular installations, require some means for maintaining the pressure in the return passage system, and particularly at the return line system inlet port, at a level which is not readily affected by acceleration (and deceleration) of. the vehicle or by changes in the attitude of the vehicle. It is a primary objective of this invention to provide a means for maintaining the pressure within a fuel system return line system at a value which is unaffected by, and is capable of substantially ignoring, inertial effects on the fuel caused by changes in the attitude or speed of the associated vehicle. It is a further object of the present invention to provide such a means which is low in cost, reliable in operation and which is fully compatible with fluidic systems. It is a still further object of the present invention to provide a device for a fluidic fuel system which is capable of isolating the fluidic control circuitry from the back pressure effects of inertial forces and attitude changes on the fluid in the returnline portion of the systems. It is a still further object of the present invention to provide a means for isolating the fluidic control circuitry from back pressure effects while preserving the general advantages of fluidics,

namely few or no moving parts.

SUMMARY OF THE INVENTION The presentinvention comprises the addition to the fluid return system of a jet pump operative to'cause the fluid return passages and fluid vents or clumps of the associated fluidic amplifier computing system to be exposed to a low or suction pressure and further operative to cause the fluid in the return-line system downstream of the jet pump to be energized sufficiently to overcome the inertial force and attitude changes referred to hereinabove. The jet pump is energized by a by-pass fluid flow from the pressurized side of the fluid system pump and, by entrainment, is operative to aspirate excess fluid from the fluidic computing means and to cause it to enter the fluid return at a somewhat elevated pressure level thereby isolating the fluidic control portion of the system.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 shows a schematic drawing of a representative fuel supply system incorporating the preferred embodiment of the present invention.

FIG. 2 shows a sectional view of a jet pump suitable for use in a system as shown in FIG. 1.

' DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT v The computing and metering means 16 are illustrated as being comprised of a computation means illustrated as fluidic amplifier 10, a fuel nozzle 26, and an air intake 28 having air flow sensing means in the form of venturi 30. The air flow sensing means 30 are connected to a control port 32 of the fluidic element and are operative to proportion the fuel flow through outlet passages 34 and 36 of the amplifier 10 in accord with the engine fuel requirements. To balance the signal to the fluidic element, passage 31 communicates control port 33 to the intake mainfold 28 upstream of the venturi 30. This is merely illustrative of a system having a single control input. However, more complete and complex systems are known and in such systems, the inertial effects upon the fuel in the return system become more critical. Outlet passage 36 is connected to nozzle 26 to provide metered fuel to the air intake 28 for ultimate supply to an engine, not shown. The fluidic amplifier 10 is also illustrated as having a pair of vents 38 and 40 which are connected via passage system 42 to the outlet passage 34. The particular computation means shown is intended to'be merely illustrative of fluidic computation means utilizing at least one fluidic amplifier and having at least one control input signal. Furthermore, the type of fluidic element shown is intended to be illustrative rather than definitive of a fluidic amplifier having utility for controlling fluid flow in the illustrated embodiment.

Referring now to FIGS. 1 and 2, and particularly to FIG. 2, the jet pump used in the present invention as the isolating means 18 is illustrated. The jet pump is comprised of a body 50 having a fluid receiving chamber 52 located therein. The chamber 52 communicates via ports 54 with the excess fluid passage system 42. A nozzle 56 is centrally located to expel a jet of pressurized fluid into the chamber 52 while aperture or port 58 is arranged to receive the jet of fluid and to exhaust it from the chamber. Nozzle 56 is in communication via passage 20 with a source of pressurized fluid which, in this instance, is the output or high pressure side of fuel pump 12 and aperture 58 is in communication via conduit or passage 24 with a fluid dump or reservoir In the embodiment described, the fluid reservoir is the fuel tank 14 but the man skilled in the art will recognize that other operating fluids and hence other reservoirs and sourcesmay be utilized in the practice and application of my invention. For instance, a system which uses air as the operation fluid would be supplied from a compressed air source or air motor while using the atmosphere as a fluid dump and systems using water would look to the water pump for a source and could then use the fluid supply as the fluid dump.

OPERATIONOF THE PREFERRED EMBODIMENT Upon energization of the fluid pumping means 12, fluid is drawn from the tank 14 and supplied under pressure to the computing and metering means 16 and the supply conduit 20 of the isolating means 18. The fluid utilized in the computing and metering means 16 may be acted upon by various command signals, here represented by signals indicative of air flow through the intake manifold 28 of an internal combustion engine, not shown. In the operation of the system, fluid in excess of that required for flow through outlet passage 36 will be directed into the excess fluid return passage system 42 from the various fluidic element vents as at 38 and 40 and from the outlet passage 34. The fluid directed into the conduit 20 will be ejected by nozzle 56 into chamber 52 and will be received by aperture 58. By fluid entrainment principles, the pressure within chamber 52 will be reduced whereby fluid in the excess fluid conduit system 42 will be drawn into chamber 52 through the various ports 54 provided for that purpose. As this excess fluid enters the chamber 52 it also is entrained and flows with the supply fluid into the aperture 58 to be returned to the fluid dump. In this manner, the isolating means 18 in the form of the jet pump will effectively aspirate the excess fluid passages and the fluid vents of the fluidic flow control portion of the system. Any fluid entering the aspirated regions will be immediately drawn into the jet pump and forced into the return line 24 at an elevated pressure.

The effects of this are twofold. Firstly, the fluidic devices will be exposed to a substantially uniform suction in the excess fluid portions of the system permitting the system designer to ignore the consequences of vehicular motion in designing a system for an automobile. Secondly, the fluid within the return system downstream of the isolating means 18 will be at an elevated pressure or energy level such that the inertial forces on the return line fluid will be effectively masked and will not be apparent upstream of the isolating means 18.

Iclaim:

1. In a fluidic system having a fluid source, a fluid pressurizing means, means for producing a fluid flow in excess of the flow required to control a further utilization means and return passage means to return excess fluid to the fluid source, the improvement comprising active isolating means interposed in said return passage means downstream of said fluidic excess flow means wherein said active isolating means are operative to isolate the fluidic excess flow means from back pressure effects caused by fluid in the return passage means, said active isolating means comprising fluid receiving means communicating with said excess fluid flow means and operative to receive fluid therefrom and energized means associated with said fluid receiving means operative to elevate the energy level of the received fluid whereby said received fluid is not influenced by inertial forces.

2. The system as claimed in claim 1 wherein said means to elevate the energy level of the received fluid comprise pump means operative to accelerate the received fluid into the return passage means downstream of the fluid receiving means.

3. The system as claimed in claim 2 wherein said pump means comprise a jet-pump having a nozzle communicating with a source of fluid under pressure.

4. In a fluidic system having a fluid source, means communicating with the source for producing a fluid flow in excess of the fluid flow required to control a utilization means and return passage means communicating with the source to return excess fluid to the source, the improvement comprising energized isolating means interposed in said return passage means downstream of said fluidic excess fluid flow means wherein said isolating means are operative to isolate the fluidic excess fluid flow means from back pressure effects caused by fluid in the return passage means, said energized isolating means comprising fluid receiving means communicating with said excess fluid flow means operative to receive fluid therefrom, and suction means coupled to said fluid receiving means operative to draw fluid from the'fluidic excess fluid flow means into said fluid receiving means.

5. The system as claimed in claim 4 wherein said suction means and said fluid receiving means are situated in proximity to the fluidic excess fluid flow means such that the fluid flow distance between the energized isolating means and the fluidic excess fluid flow means is very small compared to the fluid flow distance between the energized isolating means and the fluid source. p i

6. The system as claimed in claim 4 wherein said suction means comprise a jet pump operative to aspirate said receiving means whereby a low pressure region is formed therein. 

1. In a fluidic system having a fluid source, a fluid pressurizing means, means for producing a fluid flow in excess of the flow required to control a further utilization means and return passage means to return excess fluid to the fluid source, the improvement comprising active isolating means interposed in said return passage means downstream of said fluidic excess flow means wherein said active isolating means are operative to isolate the fluidic excess flow means from back pressure effects caused by fluid in the return passage means, said active isolating means comprising fluid receiving means communicating with said excess fluid flow means and operative to receive fluid therefrom and energized means associated with said fluid receiving means operative to elevate the energy level of the received fluid whereby said received fluid is not influenced by inertial forces.
 2. The system as claimed in claim 1 wherein said means to elevate the energy level of the received fluid comprise pump means operative to accelerate the received fluid into the return passage means downstream of the fluid receiving means.
 3. The system as claimed in claim 2 wherein said pump means comprise a jet-pump having a nozzle communicating with a source of fluid under pressure.
 4. In a fluidic system having a fluid source, means communicating with the source for producing a fluid flow in excess of the fluid flow required to control a utilization means and return passage means communicating with the source to return excess fluid to the source, the improvement comprising energized isolating means interposed in said return passage means downstream of said fluidic excess fluid flow means wherein said isolating means are operative to isolate the fluidic excess fluid flow means from back pressure effects caused by fluid in the return passage means, said energized isolating means comprising fluid receiving means communicating with said excess fluid flow means operative to receive fluid therefrom, and suction means coupled to said fluid receiving means operative to draw fluid from the fluidic excess fluid flow means into said fluid receiving means.
 5. The system as claimed in claim 4 wherein said suction means and said fluid receiving means are situated in proximity to the fluidic excess fluid flow means such that the fluid flow distance between the energized isolating means and the fluidic excess fluid flow means is very small compared to the fluid flow distance between the energized isolating means and the fluid source.
 6. The system as claimed in claim 4 wherein said suction means comprise a jet pump operative to aspirate said receiving means whereby a low pressure region is formed therein. 